1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting a liquid.
2. Description of the Related Art
An ink jet system has been devised as a printing method and utilized in a wide variety of fields in recent years. In an ink jet apparatus industrially used in particular, the spread of an ink droplet formed, the film thickness uniformity, and satellites and mists generated from the ink droplet are important factors to determine print quality. These factors are affected by electrification of an ink droplet, which is caused in the course of from ejection of the ink droplet to impact of the ink droplet. Therefore, it is required to neutralize or remove the electrification of the ink droplet.
Japanese Patent Application Laid-Open No. H06-246910 discloses a printing apparatus and a printing method by which a laminatedly electrified layer on a printing object can be removed in advance for improving the quality of printing. The printing apparatus makes printing on the printing object while relatively moving a printing head with respect to the printing object. In the printing head, a static electricity removing unit is provided on a forward side in the relatively moving direction of the printing head with respect to the printing object. Accordingly, static electricity of the laminatedly electrified layer generated on a printing surface of the printing object is removed just before conducting printing on the printing object by the printing head. As the static electricity removing unit, an ionic-wind generator for generating ionic wind for electrically neutralizing electrification of the printing object is mentioned.
Japanese Patent Application Laid-Open No. H08-187842 discloses an ink jet recording apparatus capable of stabilizing a flying orbit of an ink particle to achieve stable print quality. The ink jet recording apparatus is provided with an ink micronizing unit for micronizing an ink, a charge applying unit for applying a charge to the ink particle and an electric field deflecting unit for deflecting and controlling the ink particle to which the charge has been applied by an electric field. The ink jet recording apparatus can conduct printing by causing the ink particle to be flown on a predetermined orbit owing to this construction and to reach a predetermined position of a printing object. The ink jet recording apparatus is further provided with a unit for removing a charge electrified on the printing object or a peripheral member of the printing object. As the charge removing unit, the same ionic-wind generator as in Japanese Patent Application Laid-Open No. H06-246910 is mentioned.
Japanese Patent Application Laid-Open No. 2006-181819 discloses an ink jet printer provided with a pressure chamber which sends out an ink for ejecting the ink from an ink nozzle and an air channel which adjoins the pressure chamber and introduces air controlled to a predetermined temperature into the pressure chamber to control the temperature of the ink in the pressure chamber.
According to the constructions disclosed in Japanese Patent Application Laid-Open No. H06-246910 and Japanese Patent Application Laid-Open No. H08-187842, however, it is difficult that the ionic wind generated by the ionic-wind generator is caused to enter into a narrow space between a nozzle plate in which an ejection orifice is formed and the printing object. Accordingly, it is difficult to efficiently conduct static removal of a droplet ejected from the ejection orifice on the nozzle plate. In addition, two-dimensional arrangement of ejection orifices is effective for realizing the formation of a high-quality and high-density image on the printing object. However, it is more difficult to efficiently conduct static removal of ink droplets ejected from two-dimensionally arranged ejection orifices.
The ink jet printer disclosed in Japanese Patent Application Laid-Open No. 2006-181819 is so constructed that the air channel is provided at a part adjoining an ink channel. The air is introduced for controlling the temperature of the ink in the ink channel, so that there is no effect to remove electrification of an ink droplet, which is caused in the course of from ejection of the ink droplet to impact of the ink droplet.